1. Field of the Invention
The present invention relates to a method for arranging conducting lines among the control chips in an optical disk drive, and more particularly, to a method for arranging conducting lines among the control chips in a slim-type optical disk drive.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a layout of a slim-type optical disk drive according to the prior art. Generally, the circuit board of the slim-type optical disk drive is divided into two parts. A sub-board 20 is located on a movable tray and a main board 10 is located in the housing.
The main board 10 includes an analog signal microprocessor 12, a DSP/decoder microprocessor 14, a flash ROM chip 16, and a SDRAM chip 18. A first flexible cable 15 between the two boards 10 and 20 is used for transmitting all signals between the main board 10 and the subboard 20. Therefore, no matter whether the movable tray is positioned in or out, the signals of the sub-board 20 can still reach the main board 10.
The sub-board 20 includes a spindle motor 22, a spindle motor drive 24, an optical pickup head 30, and a sliding track (not shown in FIG. 1). The optical pickup head 30 can move on the sliding track. The optical pickup head 30 includes a laser diode 32, a laser diode drive chip 34, and a photo detector chip 36. Therefore, a second flexible cable 25 is used for connecting the optical pickup head 30 with the sub-board 20 so as to transmit signals between the optical pickup head 30 and the sub-board 20.
As technology advances, the slim-type optical disk drive has been developed to increase the rotation speed of the spindle motor. This makes it more complex to control the entire optical disk drive. That is, the design of the spindle motor drive chip 24 on the sub-board 20 and the laser diode drive chip 34 and the photo detector chip 36 of the optical pickup head 30 becomes complicated. Therefore, control signals must be added in these control chips in response to the more complex design. Adding control signals means that the pin counts of these control chips increase. Thus, the conducting lines of the flexible cables 15 and 25 must also be increased.
However, the prior art flexible cables 15 and 25 conform to the current cable standard; that is, the number of conducting lines is limited. Thus such cables are inexpensive. If flexible cables not conforming to the current cable standard are required, the cost of the slim-type optical disk drive increases due to the new design of such new flexible cables with a special number of the conducting lines.